Stupid question... sorry in advance. Please help!

[DoubleOught-BMA]

Morning all. When moving from virgin brass to my full length resized brass, by COAL has increased a full .015... which is significant. Now, the case length did increase after firing obviously but only to trim length (the virgin brass was shorter than trim length). So... I elected not to trim the once fired brass yet. But... wouldnt the bullet seater still seat the bullet at the same COAL??

I assumed the bullet would essentially be sitting just further down into the now resized (and slightly longer) case. Is it common to have to adjust your seater dies after transitioning from virgin to fired brass? Also, the COAL has increased by an amount larger than the increased case length (virgin vs FL resized once fired). Shoulder length is the same on both. What am I missing?? BTW- this is Norma brass and I'm using Forster FL and seater dies in a Forster press. Help!

 

[spife7980]

There’s a lot more in play than just that one variable. It’s also harder now which can resist sizing, especially with more interference fit than necessary.

First step is to measure the bullets themselves by ogive and then by oal, you’ll see that .010 by oal is not uncommon but more than a thousandth or two by ogive is. Where a comparator hits on the ogive is right before the nose becomes the bearing surface, that’s the most consistent part of the nose to manufacture and it’s the most consistent part to measure.

 

[Midwestside]

Just a shot in the dark,
but did you by chance measure your COAL over the top of your primer and not have the primer cup seated below flush with the face of the cartridge rim?

 

[918v]

It’s your seating pressure

 

[1500varmint]

Not sure what reloading press you have, but is it possible that there's some play in the shell holder/plate?